A sandwich-type electrochemical sensor based on RGO-CeO₂-Au nanoparticles and double aptamers for ultrasensitive detection of glypican-3

A sandwich-type electrochemical aptasensor for ultrasensitive detection of glypican-3 (GPC3) was constructed using GPC3 aptamer (GPC3_Apt) labelled reduced graphene oxide-cerium oxide-gold nanoparticles (RGO-CeO₂-Au NPs) as the signal probe and the same GPC3_Apt as the capture probe. The electrochemical redox properties of CeO₂ (Ce³⁺/Ce⁴⁺) in the RGO-CeO₂-Au NPs indicate the electrochemical signals. When the target GPC3 was present, an "aptamer-protein-aptamer" sandwich structure was formed on the sensing interface due to the specific binding between the protein and aptamers, resulting in an increased electrochemical redox signal detected by differential pulse voltammetry (DPV) technique. Under optimal conditions, the established aptasensor exhibited a logarithmic linear relationship between the current response and GPC3 concentration in the range 0.001-100.0 ng/mL, with a minimum detection limit of 0.74 pg/mL. Using the spike-recovery tests for measurement of the human serum samples, the recovery was from 99.26 to 114.01%, and the RSD range was 3.04 to 5.34%. Furthermore, the sandwich-type electrochemical aptasensor exhibited excellent performance characteristics such as good stability, high specificity, and high sensitivity, demonstrating effective detection of GPC3 in human serum samples and can be used as a clinical detection tool for GPC3.